1. Field of the Invention
The invention relates to autonomous mobile devices and more particularly to self-powered and self-guided surface treating apparatus for treating a surface, such as a floor.
2. Description of the Related Art
Despite a large potential market, autonomous mobile surface treating devices have not been commercially successful to date. Over the years, developers have repeatedly attempted to automate cleaning appliances with highly kinetic cleaning parts such as floor scrubbers and vacuum cleaners. For example, U.S. Pat. No. 5,815,880, issued Oct. 6, 1998 to Nakanishi, discloses a microprocessor controlled cleaning robot wherein rotating scrub pads dispense a cleaning solution. U.S. Pat. No. 5,940,927, issued Aug. 24, 1999 to Haegermarck et al., discloses a microprocessor-controlled autonomous surface cleaning apparatus wherein a rotating brush roller is reversed after it is entangled or blocked. Such autonomous cleaning appliances with highly kinetic cleaning parts are inherently complex and expensive. In addition, a substantial amount of energy is required to move the highly kinetic cleaning parts. Thus, such autonomous cleaning appliances require a large battery capacity to provide even a short duration of use. Moreover, being highly kinetic, these parts may present a safety concern when used around children or pets.
Autonomous mobile cleaning devices with passive cleaning parts are also known. For example, Japanese Unexamined Patent Publication Hei 11-178764 (Japanese Patent Application Hei 9-394774) published Jul. 6, 1999 and Japanese Unexamined Patent Publication Hei 11-178765 (Japanese Patent Application Hei 9-364773) published Jul. 6, 1999, hereinafter referred to as the Ichiro applications, each disclose a xe2x80x9csmall and simple cleaning robotxe2x80x9d having a deformable, dome-shaped cover provided with contact switches that are activated by the deflection of the cover when the robot runs into obstacles. Four separate contact switches, i.e., front, left side, rear and right side, are mounted on the lower portion of the robot frame adjacent the cover. The reliability of the switches depends on the amount of deflection of the cover and the location of the deflection of the cover relative to the switches. For example, if deflection of the cover occurs between two of the switches, the deflection may not be enough to activate the switches. Increasing the number of switches would reduce this problem, but at greater expense and complexity. The robot has independent left and right drive wheels, independently controlled by a microprocessor, that allow the robot to rotate when a collision is sensed by contact switches actuated by deformation of the cover. The robot is also provided with a spring-loaded plate with an upward camber fore and aft which is used to press a xe2x80x9cpaper mopxe2x80x9d onto a floor surface. The paper mop absorbs dust and rubbish from the floor surface. A spring-biased catch clip is mounted to the spring-loaded plate and is used to removably attach the paper mop. Because the deformable cover has a substantial ground clearance, the robot does not sense low-lying obstacles such as floor-mounted heating, ventilation and air conditioning (HVAC) ducts, electric cords, and transitions to carpet. When raised by such a low-lying obstacle, the spring-loaded plate tends to lift the drive wheels, causing the robot to stall. In addition, because the robot departs from a circular shape, i.e., the cover is depicted as oval in a plan view, it is more likely to become trapped when rotation is not possible due to closely spaced obstacles such as adjacent chair and table legs. The wheeled robot further poses an underfoot hazard by virtue of having freely rotating wheels that would cause the robot to act like a roller skate, i.e., xe2x80x9cskate-outxe2x80x9d, if stepped upon. Though the left and right drive wheels are connected to motors through a belt drive system, little resistance is offered to this skating action. Also, no allowance is made for alternative cleaning parts beyond changing the paper mop.
In a separate line of development, self-propelled toys capable of some degree of autonomous operation have long been known. An early example is reflected in U.S. Pat. No. 367,420, issued Aug. 2, 1887 to Luchs, which describes a clockwork toy carriage that having obstacle sensing bumpers on each end that mechanically reverse the toy""s direction of travel upon collision. More recently, U.S. Pat. No. 2,770,074, issued Nov. 13, 1956 to Jones et al., hereinafter referred to as the Jones et al. patent, discloses a compact, self-propelled toy which circumvents obstructions by rotating and moving away from obstacles upon contact by mechanical feelers. Rotation is accomplished by the use of laterally positioned, independent drive wheels, which, when driven in opposite directions, cause the circular toy to rotate around its vertical axis before proceeding thereby allowing the toy to rotate away from obstacles after collision rather than simply reverse its direction. Unfortunately the feelers, which protrude from the circular shell, are prone to catch on obstacles. Moreover, there is no teaching in the Jones et al. patent that the toy might be equipped with active or passive cleaning parts.
Programmable toy robot kits are also well known in the art. These kits such as the Lego Mindstorms Robotic Invention System require assembly and programming. They are directed to the educational value of building robots and require a knowledge of programming. In the same vein, the text, Mobile Robots, 2nd Edition (Joseph L. Jones et al., published by A. K. Peters, Natick, Mass., 1999) teaches how to build a xe2x80x9cRug Warriorxe2x80x9d robot having a circular shape in order to be able to rotate while in contact with an obstacle, and provided with contact switches that are depressed by the robot""s cover when the cover is deformed during a collision with an obstacle. Mobile Robots teaches how a robot may be programmed to circumvent obstacles by programming backing and rotation when the cover collides with an obstacle. The Rug Warrior kit, which has been described in a variety of forms from at least 1994, requires substantial technical expertise to assemble and is not sold equipped with active or passive cleaning parts.
As sold the Rug Warrior kit is equipped with a thin, deformable cover attached to the chassis with three short, flexible tubes. The cover clearance is not adjustable and is typically more than 0.33 (⅓) inch above a hard surface floor. As a consequence, the Rug Warrior does not sense low obstacles and frequently rides up over HVAC ducts, carpet transitions, and electric cords becoming hung up as low parts of the rigid chassis contact the obstacles, making unattended use problematic. As in the Ichiro patents, Mobile Robots teaches mounting separate contact switches to lower portions of the rigid chassis adjacent the cover. The reliability of the switches depends on the amount of deformation of the cover and the location of the deformation of the cover relative to the switches. For example, if deflection of the cover occurs between two of the switches, the deflection may not be enough to activate the switches. Further, the flexible tubes do no precisely locate the cover relative to the chassis. This problem is aggravated when the cover or flexible tubes become distorted, e.g., through exposure to excessive heat. Accordingly, the cover may remain pressed against at least one of the contact switches giving a false, continuing indication of a collision. Increasing the number of switches, and increasing the spring constant of each switch to better release the switch contacts, would reduce the reliability problem but at greater expense and complexity. Also as in the Ichiro et al. applications, the wheeled Rug Warrior poses an underfoot hazard by virtue of having freely rotating wheels that would cause the robot to skate out if stepped upon. Though the left and right drive wheels are connected to motors through a drive system, little resistance is offered to this skating action. Further, the thin, deformable cover may fracture to create sharp edges that present the possibility of injury.
An object of the invention is to provide an enhanced autonomous mobile surface treating apparatus.
Another object of the invention is to provide an autonomous mobile surface treating apparatus that can alternatively provide a plurality of different surface treatment modules.
Another object of the invention is to provide an autonomous mobile surface treating apparatus that avoids being hung up on low obstacles.
Yet another object of the invention is to provide an autonomous mobile surface treating apparatus having an improved collision detection sensor that is more reliable and can be inexpensively produced.
Still another object of the invention is to provide an autonomous mobile surface treating apparatus that can be inexpensively produced, preferably using toy manufacturing processes and materials.
Yet still another object of the invention is to provide an autonomous mobile surface treating apparatus that reduces the risk of xe2x80x9cskate-outxe2x80x9d if stepped upon.
One aspect of the invention is directed to an autonomous mobile surface treating apparatus that comprises a chassis, a drive mechanism mounted to the chassis by a suspension, and a substantially rigid shell movably mounted to the chassis. The suspension includes a resilient member interposed between the drive mechanism and the chassis so that when the shell is pushed toward the supporting surface with a predetermined force the resilient member compresses to permit the drive mechanism to move and the shell and/or the chassis to contact the supporting surface. This arrangement reduces the risk of the autonomous mobile surface treating apparatus xe2x80x9cskating-outxe2x80x9d if the stepped upon.
A second aspect of the invention is directed to an autonomous mobile surface treating apparatus that comprises a chassis having a plurality of elongated openings and a substantially rigid shell movably attached to the chassis by a plurality of elongated elastic supports received in the plurality of elongated openings. This arrangement provides substantially free horizontal, but vertically constrained, movement of the shell relative to the chassis. Preferably, this arrangement is used in conjunction with a collision detection sensor having a passive portion attached to a central portion of the rigid shell and an active portion attached to the chassis. This collision detection sensor used in conjunction with a rigid cylindrical shell is more reliable and can be inexpensively produced.
A third aspect of the invention is directed to an autonomous mobile surface treating apparatus that comprises a chassis, a substantially rigid shell movably attached to the chassis, and a non-skid lower edge member movably attached to the shell to adjust a clearance between the non-skid lower edge member and the supporting surface. Preferably the clearance is less than 0.33 inches. This reduces the likelihood that the autonomous mobile surface treating apparatus will become hung up on low obstacles.
A fourth aspect of the invention is directed to an autonomous mobile surface treating apparatus that comprises a chassis having a vacant volume that defines a surface treatment module receiving area adapted to removeably receive a surface treatment module. Preferably, the surface treatment module receiving area is adapted to receive a plurality of types of surface treatment modules. More preferably, a pressure adjusting mechanism is used whereby a surface treating pad applies an adjustable pressure to the supporting surface based on frictional characteristics of the supporting surface.
A fifth aspect of the invention is directed to a surface treatment module adapted to be removably received in a surface treatment module receiving area of an autonomous mobile surface treating apparatus. The surface treatment module comprises a vertical member having a first end and a second end, a surface treating pad attached to the second end of the vertical member, and an attachment mechanism adapted to removeably attach sheet-type surface treating means to the surface treating pad.